On July 2, 1996, a short circuit on a 345-kV line in Wyoming started a chain of events leading to a breakup of the western North American power system. Five islands formed with controlled and uncontrolled load shedding, uncontrolled generation tripping, and with a blackout in southern Idaho. Modern computer and communication technologies greatly facilitated dissemination of information, analysis, report writing, and event simulation for the July 2 cascading outage.